Google Search Autocomplete API allows you to get suggestions for a keyword. These are the same suggestions that you can see in Google Search when you try to search for something and Google tries to autocomplete your keyword.

API Parameters:

parameter	value
query	keyword (string)	the keyword you want to get suggestions for
gl	us (string)	parameter defines the country code for which you want to get keyword suggestions. The list of supported codes can be found here.
hl	en (string)	parameter defines the language code for which you want to get keyword suggestions. The list of supported languages can be found here.
client	chrome (string)	The list of supported clients with more information can be found here.